Due to the fast pace at which IoT is evolving, there is an increasing need to support over-theair software updates for security updates, bug fixes, and software extensions. To this end, multiple over-the-air techniques have been proposed, each covering a specific aspect of the update process, such as (partial) code updates, data dissemination, and security. However, each technique introduces overhead, especially in terms of energy consumption, thereby impacting the operational lifetime of the battery constrained devices. Until now, a comprehensive overview describing the different update steps and quantifying the impact of each step is missing in the scientific literature, making it hard to assess the overall feasibility of an over-the-air update. To remedy this, our article analyzes which parts of an IoT operating system are most updated after device deployment, proposes a step-by-step approach to integrate software updates in IoT solutions, and quantifies the energy cost of each of the involved steps. The results show that besides the obvious dissemination cost, other phases such as security also introduce a significant overhead. For instance, a typical firmware update requires 135.026 mJ, of which the main portions are data dissemination (63.11 percent) and encryption (5.29 percent). However, when modular updates are used instead, the energy cost (e.g., for a MAC update) is reduced to 26.743 mJ (48.69 percent for data dissemination and 26.47 percent for encryption).

中文翻译：

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物联网中的无线软件更新：关键原则概述

由于物联网发展速度很快，因此越来越需要支持无线软件更新以进行安全更新、错误修复和软件扩展。为此，已经提出了多种无线技术，每种技术都涵盖更新过程的特定方面，例如（部分）代码更新、数据传播和安全性。然而，每种技术都会引入开销，尤其是在能耗方面，从而影响电池受限设备的使用寿命。到目前为止，科学文献中缺少描述不同更新步骤和量化每个步骤影响的全面概述，因此很难评估 OTA 更新的整体可行性。为了解决这个问题，我们的文章分析了物联网操作系统的哪些部分在设备部署后更新最多，提出了一种在物联网解决方案中集成软件更新的分步方法，并量化每个相关步骤的能源成本。结果表明，除了明显的传播成本外，安全等其他阶段也引入了大量开销。例如，典型的固件更新需要 135.026 mJ，其中主要部分是数据传播 (63.11%) 和加密 (5.29%)。然而，当改为使用模块化更新时，能源成本（例如，MAC 更新）会降低到 26.743 mJ（48.69% 用于数据传播，26.47% 用于加密）。并量化每个相关步骤的能源成本。结果表明，除了明显的传播成本外，安全等其他阶段也引入了大量开销。例如，典型的固件更新需要 135.026 mJ，其中主要部分是数据传播 (63.11%) 和加密 (5.29%)。然而，当改为使用模块化更新时，能源成本（例如，MAC 更新）会降低到 26.743 mJ（48.69% 用于数据传播，26.47% 用于加密）。并量化每个相关步骤的能源成本。结果表明，除了明显的传播成本外，安全等其他阶段也引入了大量开销。例如，典型的固件更新需要 135.026 mJ，其中主要部分是数据传播 (63.11%) 和加密 (5.29%)。然而，当改为使用模块化更新时，能源成本（例如，MAC 更新）会降低到 26.743 mJ（48.69% 用于数据传播，26.47% 用于加密）。